Salvador G. Garcia, UGR
FDTD TECHNIQUES TO SIMULATE COMPOSITE AIR
VEHICLES FOR EMC• Luis D. Angulo – University of Granada• Sandra Greco – University of Rome La Sapienza• Miguel Ruiz Cabello – University of Granada• Salvador G. García – University of Granada• Maria Sabrina Sarto – University of Rome La Sapienza
Partially supported by:
Salvador G. Garcia, UGR
OUTLINE• MOTIVATION
• CEM in EMC: PROJECT
• CFRC COMPOSITES: EQUIVALENT MIBC• TIME DOMAIN: MIBC FOR FDTD• EXAMPLES• STABILITY, CAUSALITY AND PASSIVITY• MIBC FOR FEM: DGTD• CONCLUSIONS
Salvador G. Garcia, UGR
MotivationUSE OF COMPOSITES IN AIRCRAFTS
Salvador G. Garcia, UGR
CEM EMCNEED OF HIGH PERFORMANCE COMPUTER TOOLS
Full Wave Time Domain: BROADBAND
• FDTD is able to handle COMPLEX 3D (Dispersive, Anisotropic, Non-Linear, PML…)
• DGTD is a highly accurate alternative to FDTD
REQUIRE VOLUMIC MESHING ► HIGH CPU/MEMORY• SUBCELL MODELLING NECESSARY TO REDUCE
COMPUTATIONAL COSTS (THIN-XXXXX)– THIN-LAYERS, THIN-SLOTS, THIN-WIRES
44 EUROPEAN PARTNERS: SYNTHETIC FRAMEWORK
Salvador G. Garcia, UGR
CFRC LAMINATESEQUIVALENT LAYER MODEL
( ) ( ) ( ) ( )( ) ( ) ( ) ( )
front fr bkfront back front front
bk fr backfront back back back
Z Z HZ ZH H H
NORMAL INCIDENCE IN A MULTILAYER:
MIBC
Salvador G. Garcia, UGR
MIBC enables:- To model field penetration trough conducting
structures;- To predict diffusion of magnetic field in conducting
enclosures;- To predict redistribution effect of electromagnetic field in
conducting enclosures.
D'Amore, M.; Sarto, M.S.; , "Theoretical and experimental characterization of the EMP-interaction with composite-metallic enclosures," Electromagnetic Compatibility, IEEE Transactions on , vol.42, no.2, pp.152-163, May 2000
MIBC vs SIBC
Salvador G. Garcia, UGR
1 1
( ) ( ) ( ) ( )k
N Np tk
kk kk
RZ Z Z t Z t R e u tj p
( ) ( ) ( ) ( ) ( ') ( ') 't
E Z H E t Z t t H t dt
Frequency dispersion VECTOR-FITTED as the sum of complex-conjugate pole-residue pairs fractions
IMPEDANCE BOUNDARY CONDITIONS
FOR RESULTS IN THIS WORK THE CODE IS PROVIDED BY
CONVOLUTION
Salvador G. Garcia, UGR
FDTD EMC HIRF SOLVER• Yee Cell Structured mesh• Finite Difference in space.• Leap Frog in Time.
• Very simple explicit algorithm• MPI parallel• Locally conformal (with Dey-Mittra stabilization)
www.ugrfdtd.esUGR PARALLEL HPC
FDTD&
UGR HOLLAND-BERENGER MULTIWIRE
BUNDLE SOLVER+
URM MIBCTHIN-PANEL SOLVER
Salvador G. Garcia, UGR
M. S. Sarto, “A new model for the FDTD analysis of the shielding performances of thin composite structures,” IEEE Trans.Electromagn. Compat., vol. 41, no. 4, pp. 298–306, Nov. 1999.
e. g. carbon fiber composites, graphene ► anisotropy
,0 ,0 , ,00
,0 ,0 , ,00
, , ,
, ,
( )( )( )( )
( ) , ( )- ( )( )- ( )( )
ISO ANI ISO ANIy y y t y tzyANI ISO ANI ISOz z z t z tyz
ISO ANI Izdyd y t y t y d
ANI ISOydzd z t z t
Z Z Z ZHZ Z Z ZH
Z ZH Z Z ZH Z Z
,
, ,
SO ANIy d
ANI ISOz d z d
ZZ Z
0ANIZ
DISPERSIVE ANISOTROPIC MIBC
1/2,... 1/2,...n ni iHz Hz
TIME DOMAIN
NOT YEE’sYEE’s
1 11, 2, 3,
1
,N
n n n n n n nk k k k k k
K
E Z H q q H q H
CO-LOCATED IN TIME AND IN SPACE!
PIECEWISE LINEAR RECURSIVE CONVOLUTION
DUPLICATED UNKNOWNS
Salvador G. Garcia, UGR
EXPLICIT SCHEME
Salvador G. Garcia, UGR
Prepreg copper mesh 10 POLES VF
SIMULATIONANALYTICAL
RESULTS: ISOTROPIC
Salvador G. Garcia, UGR
RESULTS: ISOTROPIC
SIMULATION (Gaussian pulse derived)ANALYTICALSIMULATION (Gaussian pulse)
CFC (0.5 mm, 0º) + WOOD (5 mm) + CFC (0.5 mm, 90º)20 POLES VF
Salvador G. Garcia, UGR
Aluminum foil (0.3 mm) Measurements in a dual reverberating chamber
RESULTS: ISOTROPIC
Salvador G. Garcia, UGR
COPPER MESH4 POLES VF
RESULTS: ANISOTROPIC
TE SIMULATIONTM SIMULATIONTE ANALYTICALTM ANALYTICAL
Salvador G. Garcia, UGR
SENSITIVITYANISOTROPIC MESHED MODEL
Freq
SE
(dB
)
PBC
PBC
PBC
PBC PBC PBC
PBC
PBC
Salvador G. Garcia, UGR
LATE-TIME INSTABILITIES!
ENSURE• STABILITY• CAUSALITY• PASSIVITY
STABILITY Boundedness
( ) analytic 0 iffZ -1
lim Z(t)
Z(t) =Fourier ( )t
Z
Trivial!
CAUSALITY Response AFTER excitation
1
( ) ( ) ( )N
kr i
k k
RZ Z Z j Zj p
( )lim 0
( )1( ) ''
( )1( ) ''
ir Cauchy
ri Cauchy
Z
ZZ P d
ZZ P d
KRAMER-KRONIG
Automatic! Re 0kp
Salvador G. Garcia, UGR
PASSIVITY
( ) 0 , ( )=Eigenvalues ( ) ( ) Reals HZ Z
( ) 0 , 0 , 1...4iiZ i
NOT AUTOMATIC IN VECTOR-FITTING!
WORKAROUND IN LEAP-FROG:
• Tune number-of-poles, band fitting• Stable time-step GREATER than maximum
Nyquist period for non-passive behavior
• Other conditions for Runge-Kutta | ( ) 0 COURANTt t
Min
Salvador G. Garcia, UGR
ACCURATE ALTERNATIVE TO FDTD : DGTDThe field is allowed to be DISCONTINUOUS at the boundaries
• COMMUNICATE ADJACENT ELEMENTS THROUGH NUMERICAL FLUXES• QUASI-EXPLICIT • DOES ANYTHING FDTD DOES! (DISPERSIVE, SIBC, etc.)
DISCONTINUOUS GALERKIN FEM
Size ~ q2 ,q=Basis order Flux terms
Salvador G. Garcia, UGR
MIBC MMT FOR DGTD
MODIFY the flux conditions for PEC:
with
PEC, PMC FLUX CONDITIONS
PLRC TIME DOMAIN
Salvador G. Garcia, UGR
SIBC MMT FOR DGTD
VALIDATION: ISOTROPIC CASE
Salvador G. Garcia, UGR
REAL AIRCRAFT
FDTD:cells: 703.704.332d.o.f: 4.394.792.584 DGTD:elements: 8.845.279d.o.f: 966.682.616
freq (MHz)
Cur
rent
inca
ble
(A)/
Ein
(V/m
)
100 101 102 10310-5
10-4
10-3
10-2
FDTDDGTD
freq (MHz)
Hto
tal/
Hin
100 101 102 10310-3
10-2
10-1
100
101
FDTDDGTD
Salvador G. Garcia, UGR
MECHANICAL MODEL
MESH/REPAIR
INPUT/OUTPUT FILE (HIRF-SE STANDARD)
MTLN CRIPTE+MPI HPC PARALLEL SOLVERS: EMC, RCS, ANTENNAS, etc.
CONCLUSIONSVALIDATED TOOL FOR HIRF-SE CERTIFICATION OF METALIC AND COMPOSITE AIRCRAFTS
Salvador G. Garcia, UGRTHANK YOU!
UPCOMING:
+
Salvador G. Garcia, UGR
UGRFDTD• Periodic BC, PEC, PMC, CPMPL ABCs• Uneven mesh spaced grid• N-pole/residues nth order frequency dependent materials Sub-cell single-
conductor cable model and junctions (multiconductor ongoing) • Resistive loading of cables • Lossy anisotropic materials • Thin Slots • Bi-anisotropic, periodic, DNG media (ongoing)• Excitations: plane wave, dipoles, cable voltage sourceMixed MPI
paralellization/OpenMP• Portable: Tested in Cray-PGI, Sunstudio Fortran, Intel Fortran, GNU fortran• GUI: GiD (ongoing), interim: CADFIX.
• Coupled with CRIPTE cable bundle solver (ongoing through )• Coupled with IELF and FSV (through )